Process for revitalizing discarded plaster-of-paris.



JOHN E. EASTWIGK, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS FOR REVITALIZING DISCARDED PLASTER-OF-PARIS.

Specification of Letters Patent.

Patented Sept. 15, 1908.

Application filed April 13, 1907. Serial No. 367,949.

To all whom it may concern:

Be it known that I, JOHN E. EASTWICK, a citizen of the United States,residing at Philadelphia, in the county of Philadelphia and State ofPennsylvania, have invented certain new and useful Improvements inProcesses for Revitalizing Discarded Plaster-of-Paris, of which thefollowing is a specification.

My invention has for its object to provide for revitalizing plaster ofparis, that is to render the same, after having been previously utilizedor discarded, capable of being re-used which is a desideratum in the useof this material, especially in view of the great waste attending suchuse as now eXpericnced.

In carrying out my invention, I may take old molds, casts and the likeof plaster of paris which material contains about 20 of Water ofcrystallization and about the same proportion of saline Water. Thismaterial so constituted is then broken up into small' pieces and putinto a drier, whereby the water of crystallization is driven off andabout one-half of the saline water. ,This saline water is the Waterabsorbed by the foreign salts contained in the material. The latter arethen immersedin a liquid or solution of sulfuric acid, ground alum andwater, in the proportions of a half gill of the sulfuric acid 66% pure,four (4) ounces of the alum and one (1) gallon of water. In mixing thissolution I find it preferable to let the acid soak in water a few hoursso that the lead will precipitate to the bottom, and then the acid atthe top is poured off into the alum and water solution. After havingbeen thoroughly saturated in this solution, say about two (2) hours,said pieces of plaster of paris are removed therefrom and placed in asuitable kiln for properly calcining or drying such plaster of parispieces, after which they are suitably pulverized and the resultingproduct is ready for placing on the market for sale. The user, ofcourse, will suitably gage the material with water in the usual way ofconverting it into a plastic condition as in utilizing or employing thesame inane arts or for the intended purpose. This has proven bypractical experience to effect the re-vitalizing of plaster of paris assuch, which has been previously used, whereby much wasted or discardedmaterial of this character may be re-converted and appropriated forre-using as will be appreciated.

In cases when it may be desired to obtain a plaster which may set veryslowly but which shall obtain a greater hardness than ordinary plaster,this may be effected by dissolving one (1) ound of ground glue in thewater with which this composition may be gaged.

I claim 1. A herein described process of treating waste hydrated sulfateof lime, which consists in first drying it and then saturating 1t in asolution of sulfuric acid, alum and water, and then calcining saidmaterial.

2. A herein described process of treating waste hydrated sulfate oflime, which consists in drying it in broken up form and then saturatingit in a solution of sulfuric acid, alum and water, and then calciningsaid material.

3. A process of treating waste hydrated sulfate of lime, which consistsin first partially drying the pieces, then saturating said pieces in asolution of sulfuric acid, alum and water, and then placing the materialin a kiln and calcining.

4. A herein described process of treating waste hydrated sulfate oflime, which consists in drying the pieces of waste material and causingthe water of crystallization to be driven therefrom and a portion of thesaline water, and then saturating the material in a solution of sulfuricacid, ground alum and water, and then placing the material in a kiln andcalcining.

5. A process of treating waste hydrated sulfate of lime, which consistsin first dryin it and then saturating it in a solution of su furic acid,alum, water and glue, and then calcining said material.

' In testimony whereof I afiix my signature, in presenceof twowitnesses.

' JOHN E. EASTWICK.

Witnesses:

BENNETT S. JoNEs. J. WM. MISTER.

